I know almost nothing about lightsabres, and to be honest care even less - but my understanding was that Disney did not, in fact, have access to Lucasfilm's props, only the IP. Certainly the reason put forward as to why all the astrodroids in the Disney movies are new builds (and for background droids, frequently rented from Astromech Club builders) is that Disney couldn't have the old R2-D2 props.
That story could be wrong, of course, or I could be mis-remembering, or it could be that Disney can go look at all the old props and drawing and so forth but isn't allowed to actually film the old props. But yeah, my understanding is that Disney doesn't actually have all the old LFL props and thus has to build new ones.
Anyone with further info on this subject, I'd love to hear it!